The present invention relates generally to an improved communications system and in particular to a method and apparatus for call interception in a communications system. Still more particularly, the present invention relates to a method and apparatus for providing call interception for a call using intelligent network services.
Call intercept is a mechanism of tracking subscribers based on their identification number. This mechanism is used in communications network, such as a global system for mobile communications (GSM) network. Prior to the introduction of intelligent networking (IN) into GSM networks, call interception required the identity of the mobile subscriber to be known to the monitoring agency either in the form of an international mobile subscriber identity (IMSI) or a mobile subscriber integrated services digital network number (MSISDN). With the advent of IN technology, services may be created which subscribers can access by using either their regular GSM phones or using some other access methods to trigger the services in the network. These other access methods may include, for example, a pay phone or a landline. In such an instance identification numbers recognized by the GSM network are not used to access IN services. These IN services include, for example, voice mail, personal number service (PNS), virtual private network (VPN), and geo-zone.
With call termination through an IN subscriber, the calling party need not dial the MSISDN of the GSM subscriber. Further, a mobile subscriber might hide behind some number, which is unknown to the GSM specifications. These numbers may be, for example, a virtual private number (VPN) or a personal number service (PNS) number. During call setup in a GSM-IN network, the alias numbers may not be known to the law agency.
A subscriber may be known by its IMSI or MSISDN to the law agency, but IN services have allowed the subscriber to have other numbers too. No mechanism is present in GSM networks to correlate these different numbers. For example, with an IN service that provides xe2x80x9chome services in which the subscriber has a zone called xe2x80x9chomexe2x80x9d. When the subscriber is located at xe2x80x9chomexe2x80x9d, this IN service provides a more favorable rate to a subscriber. In this area, the mobile station can receive or originate calls at a low rate. With this service IN, a local number portability (LNP) number is introduced into the GSM network. The location of the mobile station is important with this IN service. For termination calls, if the mobile station is subscribed to the service and is currently out of the home zone, all calls to the mobile station using the LNP will be routed to a voice mail number. If the mobile number is called via its MSISDN number, the mobile station can be reached anywhere independent of its position. No mechanism is present in the GSM network to map the LNP number to an IMSI or MSISDN number. As a result, tracking the subscriber becomes impossible. For originating calls using this service, a caller dials any number. If the mobile station is only identified by its LMP number, then tracking or call interceptive calls of the originator becomes difficult. As a result, a malicious mobile subscriber may allude monitoring agencies. Given this situation, a subscriber has the capability to remain anonymous to a law enforcement agency if all that is known to the law agency is the LNP number or some private number of the subscriber.
Thus, it would be advantageous to have an improved method and apparatus for providing call interception for calls involving IN services.
The present invention provides a method and apparatus for use in intercepting calls involving subscribers having numbers that are unknown within a wireless communications system. A first number is provisioned or indicated for call interception within the mobile switching center. The first number is associated with a second number. The second number is also referred to as an xe2x80x9caliasxe2x80x9d for the first number. When a call to the second number is originated at a mobile switching center from a mobile station involving a service, such as an IN service, a message is sent to a service control point that is involved in providing the service. The second number is sent in the message. A result in a return message from the service control point is received by the mobile switching center. This return message will include the first number and will result in initiation of call interception of the call.
These processes may be applied to the use of all numbers assigned to or associated with a subscriber. The numbers and the association between the numbers is stored in a database. When a call using a number is made, the database containing the numbers associated with the subscriber can be queried when a call is made to see if an alias for the number has been provisioned for call intercept. If an alias for the number has been provisioned in the database, the alias is returned to the switch handling the call. The alias also is provisioned in the switch and the return of the number is used to find an entry or data structure in the switch containing call intercept information used to initiate call intercept.
Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.